This invention relates to a novel phthalocyanine compound and a method for preparing the same, intermediates or analogues used in the method, a phthalocyanine-containing polymer obtained by starting with the novel phthalocyanine compound and a method for preparing the same. It also relates to a catalyst and an optical recording medium using such a phthalocyanine compound or polymer.
Phthalocyanines are macrocyclic dyes having a structure similar to porphyrin compounds and they are stable against light, heat and moisture, chemically stable and fast. Especially metal phthalocyanines have been widely used as dyes or pigments because of their high stability and definite color tone. They now draw interest as materials for light absorption, electric conduction, photo-conduction, energy conversion, electrode and catalyst because of the presence of a metal ion in a large K-electron conjugated system. However, they are difficult to dissolve, to work up to high purity, and to handle under ambient conditions. Currently, great attention is paid to the phthalocyanine compounds as recording material for optical recording media such as write-once compact disks (CD-R). For such application purposes, their low solubility in solvents for use in coating of a recording layer is detrimental.
Attempts were made to produce a polymer having carried thereon a phthalocyanine, especially a metal phthalocyanine for facilitating formation of films or similar items capable of exerting a high function. Such a metal phthalocyanine-containing polymer is produced, for example, by synthesizing a metal phthalocyanine derivative having a reactive group and reacting it with a polymer having introduced therein a group reactive with the reactive group (see D. Whrle et al., J. Org. Organomet. Polym., 1, 1, 115 (1991)). This type of synthetic method wherein a metal phthalocyanine derivative is reacted with a polymer, however, suffers from the problem that the reaction product has an inconsistent content of metal phthalocyanine ring.
Also proposed were metal phthalocyanine derivatives which have a vinyl group and are thus polymerizable by themselves as disclosed in Japanese Patent Application Kokai (JP-A) Nos. 184083/1985 and 53990/1987. It was also attempted to produce polymers by starting with them as disclosed in JP-A 50311/1987. The metal phthalocyanine derivatives are obtained by starting with a metal phthalocyanine tetracarboxylic acid and introducing a vinyl group therein. Synthesis of a metal phthalocyanine tetracarboxylic acid entails formation of much by-products probably because of solid-phase reaction. Also most intermediates to the vinyl group-containing metal phthalocyanine derivatives are sparingly soluble and difficult to purify. Then the final products are low in purity. While vinyl groups are introduced in a number proportional to the number of carboxy groups and thus typically four vinyl groups are introduced, often those products having vinyl groups in a number other than the desired number are concomitantly produced, which are difficult to separate and thus cause a lowering of purity. Moreover, the vinyl group-containing metal phthalocyanine derivatives are less soluble.
The resulting polymer is often a three-dimensional polymer since the metal phthalocyanine derivative has four vinyl groups as a general rule. This complies with the purpose of having a vinyl polymer carry a metal phthalocyanine like a crosslinking agent, but not with the purpose of synthesizing a linear polymer.
Therefore, it is desired to have a phthalocyanine compound having a sufficiently increased solubility to use as a recording material for optical recording media. It is also desired to develop a polymerizable phthalocyanine compound having improved solubility and purity and offering a freedom of choice of a ligand metal to the phthalocyanine. It is further desired to produce a polymer from the phthalocyanine compound as a starting monomer, the polymer having improved solubility, high purity, easy control of orientation, and a high phthalocyanine content.